Photoassociative ionization of Na inside a storage ring

TL;DR

This study compares photoassociative ionization rates of sodium atoms in a storage ring and a magneto-optical trap, revealing geometry-dependent differences in collision dynamics and ionization efficiency.

Contribution

It provides the first experimental comparison of PAI in a storage ring versus a trap, highlighting the influence of atomic sample geometry on collisional processes.

Findings

PAI rate constant is lower in the storage ring.

PAI does not show saturation in the ring, unlike in the MOT.

Collision geometry significantly affects ionization rates.

Abstract

Motivated by recent interest in low dimensional arrays of atoms, we experimentally investigated the way cold collisional processes are affected by the geometry of the considered atomic sample. More specifically, we studied the case of photoassociative ionization (PAI) both in a storage ring where collision is more unidirectional in character and in a trap with clear undefinition of collision axis. First, creating a ring shaped trap (atomotron) we investigated two-color PAI dependence with intensity and polarization of a probing laser. The intensity dependence of the PAI rate was also measured in a magneto-optical trap presenting equivalent temperature and density conditions. Indeed, the results show that in the ring trap, the value of the PAI rate constant is much lower and does not show evidences of saturation, unlike in the case of the 3D-MOT. Cold atomic collisions in storage ring may represent new possibilities for study.